1. Field of the Invention
The present invention relates to a shunt element contacting structure for decorative lamp holder, and more particularly to an elastic shunt element contacting structure for decorative lamp holder.
2. Description of the Prior Art
Decorative lamps are frequently used in many festivals. Normally, such decorative lamps are arranged to appear in the form of light strings. That is, a plurality of lamp holders are electrically connected to a pair of electrical wires in series, and each lamp holder is adapted to connect a decorative lamp thereto. Since the decorative lamps in the same light string are serially connected to each other, burning out or removal of any one of the decorative lamps from the lamp holder would cause interruption of the circuit of the whole light string and result in extinguishing of all other lamps in the light string. Meanwhile, decorative lamps usually include bulbs that normally have short usable life and tend to become damaged, and therefore require frequent replacement. For general users, such replacement of decorative lamps on a light string is extremely labor and time consuming. A lamp holder with shunt circuit has been developed in an attempt to solve the above-mentioned problem, so that current can still be supplied via a shunt when the decorative lamp mounted in the lamp holder becomes damaged or is removed from the lamp holder.
In a conventional shunt circuit, there is included a shunting wire wound between filaments inside the bulb of the decorative lamp. The shunting wire is generally made of aluminum oxide. When the filaments are burned out, the shunting wire provides a shunt path for current to flow therethrough. The above-described shunting structure is provided inside the bulb of the decorative lamp and therefore involves very complicate manufacturing process. Moreover, the above shunting structure solves only the problem of a burned-out decorative lamp in a lamp holder. That is, the lamp holder would still become open-circuited when the decorative lamp is removed from the lamp holder.
It is therefore a primary object of the present invention to provide a shunt element contacting structure for decorative lamp holder, in which a shunt element is mounted in the lamp holder instead of the decorative lamp.
Another object of the present invention is to provide a shunt element contacting structure for decorative lamp holder, in which two elastic contacting plates are adapted to automatically contact with and disengage from a shunt element mounted in the lamp holder. When the lamp holder has a decorative lamp inserted therein in a normal manner to push the elastic contacting plates outward, the shunt element is not in contact with the contacting plates for current to directly flow through filaments in the decorative lamp. And when the decorative lamp is burned out, or when the decorative lamp is removed from the lamp holder, the elastic contacting plates are in an outward projected position to contact with the shunt element, so that the shunt element provides a shunt path to avoid failure of a whole light string due to damage of any one of the decorative lamps thereof.
To achieve the above objects, in accordance with the present invention, there is provided a shunt element contacting structure for decorative lamp holder mainly including two contacting plates correspondingly fixed to an inner wall surface of a decorative lamp holder and each having an inward projected elastic portion, and a holding member radially inward extended from the inner wall surface of the lamp holder to hold a shunt element thereto. When a decorative lamp is inserted into the lamp holder with two leads in contact with the two contacting plates, the two elastic portions are also radially outward pushed by a lower portion of the decorative lamp to disengage from two ends of the shunt element on the holding member. And, when the decorative lamp is removed from the lamp holder, the elastic portions of the contacting plates resume to their radially inward projected positions to contact with two ends of the shunt element to thereby provide a shunt path.